Process for the separation of metals



Sept; 2, 19410 E. JUNKER ET AL 2,254,805

PROCESS FOR THE SEPARATION OF METALS Filed Aug. '22, 1939 m M g n5 wm W fig? L w hHA 2 cm fi m into powder.

Patented Sept. 2, 1941 UNITED STATES PATENT OFFICE PROCESS FOR THE SEPARATION OF METALS Erich Junker, Berlin-Charlottenburg, andWillibald Leitgebel, Berlin-Wilmersdori', Germany Application August 22, 1939, Serial No. 291,286

InG

ermany August 22, 1938 4 Claims. '(01. 75--63) The invention relates to the manufacture of metal powder and to the separation of metals by at least partly converting the metals into powder form. It is known that the brittleness of metals increases with increase of temperature, and is extraordinarily high just below the melting point.

According to the invention that metal which is to be converted into powder, is submitted to strain by beating, shaking, rolling, grinding or kneading at a temperature below the melting point within the range of high brittleness. Thereby the metal treated breaks down into more or less fine powder, according to the temperature,

and the strength of the mechanical forces. Hitherto metal powders have been prepared by breaking up metals without increase of temperature by cutting tools. Also metal foils have been mechanically broken up by stamping, rolling or the like or metals disintegrated by air or steam. Finally molten'metals at their melting points, during the occurrence of solidification have been disintegrated to groats by stirring. Over and above these processes the present invention offers the advantage of yielding oxide free metal powder, in a simple manner, in spite of the use of raised temperatures. I

A further feature of the invention consists in that single metals are separated from metal mix tures and also metal alloys in such a manner that the metals at least in part are converted This separating method is applicable to mixtures and alloys of metals in as far as differences of melting point of the single metals or of the alloy components occur. cording to the invention the mixture is first heated to a temperature below the melting point -''but within the temperature range of high brittleness of the lowest melting metal, and at this temperature submitted to a mechanical stressing, "e'Jg'Bby-lmpact, shaking or beating.

According to the invention the pulverised fraction of the 'metal is separated in a subsequent of the next higher melting point, and the pulverised fraction oI-the metal again separated. The process can be continued while increasin the temperatures corresponding to the melting points of the metals present until any delred metals are separated from one another.-

The process is also applicable to alloys, which consist, e. g. of a. crystal component of high melting point and one of low melting point. The alloy is first heated at a .temperature under the melting point of the crystal component of the lowest melting point but within the temperature range of high brittleness, and to this temperature submitted to a mechanical stressing, by

which the said crystal component'is pulverised.

Preferably the alloy which is to be separated into its crystal components is previously dis tegrated. The process can for example be applied to the separation of the single metalsfrom mixed tumings or chips of white metal, light metal; red brass, bronze and high melting metals.

Example 1 .Separation of a mixture of parts of lead (melting point 327 C.) and aluminum (melting point 658 (2.): The metal mixture is heated to approximately 310 C. and then mechanically stressed by shaking, beating or the like. Thereby, the lead entirely disintegrates into powder,

aluminum primary crystals and of the eutectic disintegrating to powder which contains'all the tin. The powder will be sifted from the aluminum crystals, either simultaneously or subsequently.

Example 3.-Separation of a mixture of tin (melting point 232 C.) zinc (melting point 419' 0.), aluminum (melting point 658 C.) and cop- The mixture is per (melting point 1083 C.). heated first to approximately 220 C. and mechanically stressed by beating or the like. Thereby the tin disintegrates into powder which is separated from the other metals through a' fine sieve; then, the remainder of the mixture is further heated up to about 400 C. and again mechanically stressed by beating or the like whereby the zinc disintesrates into powder and is removed by sifting. The then-remaining mixture is heated to about 640 C. and mechanically stressed by heating or the like whereby the aluminum is obtained in powder form and is removed by sifting so that, finally the copper remains and all the four metals are separated from each other. e

The apparatus for carrying out the pulverisation and separating process according to the invention can be constructed in different manners. We prefer rotating drums with inserted pins, scoops, ribs or the like, in which one of the drums can be stationary or both can rotate. The

outer drum can also be formed as a casing. Instead of this a special casing can enclose both drums. The separation of the powder may'be brought about advantageously in the same operation as the pulverisation, e. g. if the rotating drum is formed as a sieve drum.

In the drawing are shown diagrammatically three forms of apparatus for carrying out the invention.

Fig. 1 shows a drum, partly broken off, in which a shaft provided with heaters rotates.

Fig. 2 is'a diagrammatic cross section through an apparatus in which two concentric drums, provided with beaters, rotate in a single casing.

Fig. 3 shows another form in which several drums rotate besides one another.

The drum b according to Fig. 1 is so formed that its parts can be brought to different high temperatures. On feeding in a metal mixture through the feeding hoppers a into the end of the drum at the lower temperature (t1), the metal of the lowest melting point is pulverised by the action of the beating shaft. The powder is led off below through an opening 11 provided with a sieve (compare also'Fig; 3). The remaining material passes into a zone of the drum of higher temperature (is) in which the metal with the next highest melting point is pulverised and separated and so on.

In Fig. 2 are shown two concentric rotary drums f1, f2 with beaters which can be formed as sieve drums. Both drums are surrounded by a casing e.

In the form according to Fig. 3, three drums b1, b2, b1 are arranged. alongside one another. The drums of the apparatus may be kept at the same temperature, e. g. when only onev metal is,

to be pulverised. The apparatus can however also be so constructed that the first drum in has fed from one drum to another by a suitable conveyor. Y.

The process is specially suitable for the manufacture of oxide free aluminium powder, also for working up metal mixtures, in particular for separating the metals of mixed foil waste. In-

this case after separation of the lower melting burn or' carbonise, preferably with exclusion of 'carried out according to the invention first a mechanical separation in the wet way into speciflcally heavier and lighter components, e. g. by flotation. In this manner can be separated organic components and impurities, e. g. paper, and moreover a general separation into heavy metals and light metals can be carried out. The thus obtained metallic fractions can then themselves be separated into their components according to the invention in the dry way.

We declare that what we claim is:

1; Process for separating components of metal mixtures comprising heating the mixture up to a temperature below the solidus point but within the temperature range of high brittleness of the lowest melting metal, subjecting the mixture to mechanical stress to reduce the lowest melting metal to powder and separating the powder from the remainder of the mixture.

2. Process for separating components of metal mixtures, comprising heating the mixture up to a temperature below the solidus point but within the temperature range of high brittleness of the lowest melting metal, subjecting the mixture to mechanical stress to reduce the lowest melting metal to powder, separating the powder, heating the remainder of the mixture to a temperature beneath the solidus point of the metal of next highest melting point, again subjecting said remainder of the mixture to mechanical stress,

separating the metal powder thereby obtained,-

from the then remaining portion of the mixture, and-repeating the process at constantly increasing temperatures until any desired metals are separated from one another.

3. Process for separating components of alloys comprising heating the alloy up to a temperature below the solidus point but within the temperature range of high brittleness of the lowest melting crystal component, subjecting the said alloy to mechanical stress at this temperature, separating the pulverised alloy component, heating the remainder of the alloy to a temperature below the solidus point of the next highest melting component, subjecting said remainder of the alloy to stressat this temperature, separating the thereby pulverised component from the then remaining alloy components, and repeating the process at constantly increasing temperatures until any desired alloy components have been separated from one another.

4. Process of-separating metal mixtures or alloys comprising heating the mixture or alloy up metals by fractional pulverisation, finally the metal of highest melting point remaining behind, for example, aluminium, is heated to 400- to a temperature below the solidus point but' within the temperature range of high brittleness of the lowest melting metal or crystal component present, subjecting the mixture or alloy to mechanical stress to pulverise said lowest melting metal or crystal component, and at the same time separating the non-pulverised metal or alloy residue from the powdered metal or alloy component produced.

ERICH JUNKER.

WILLIBALD LEITGEBEL. 

